There are multiple options for keeping vise parallels apart. It is common to use a simple spring in small width work-piece applications. In practice, the machinist stores a variety of springs of different lengths in a large collection bin and wastes a large amount of time trying to find the correct spring among the random springs compiled in the bin. There are several alternatives to springs.
As described in U.S. Pat. No. 5,222,997 to Montgomery published in 1993 a vise is commonly used to secure work-pieces to be machined. In order to secure such work-pieces within the vise, a pair of thin, flat plates known as parallels may be used. Parallels commonly consist of metal plates of varying length and width dimensions and thicknesses. The parallels are mounted between the vise jaws and the work-piece rests on top of the parallels and between the vise jaws. Parallels serve to mount the work-piece in an exact location and may serve as a guide for a machining operation.
U.S. Pat. No. 4,558,856 to Shaffer (“Shaffer”) discloses a holder for retaining a pair of parallels against the jaws of a vise. Shaffer's device makes use of a U-shaped spring body that pivotally attaches to a pair of end members which engage the parallels. Another device as found in U.S. Pat. No. 3,891,201 to Clugage (“Clugage”) reveals a method for securing work-pieces by means of a hold down element; however, no resilient holding mechanism is disclosed.
U.S. Pat. No. 5,222,997 to Montgomery (“Montgomery”) published in 1993 teaches a holder device for selectively positioning and retaining a pair of parallels at a selected position against the opposed jaws of a vise found on a milling machine, drill press or the like. The holder device includes stationary and movable retaining members in the form of flat plates and a guide arrangement for maintaining the retaining members parallel during movement between extended and retracted positions. The guide arrangement includes two parallel spaced inner tubes attached at adjacent ends to the stationary retaining member and extending perpendicular to the length of the inner tubes together with a pair of parallel spaced outer tubes attached at adjacent ends of the second retaining member and perpendicular thereto. The outer tubes telescope over the inner tubes to provide parallel positioning for the retaining members. A force applying or bias is provided in each of the inner tubes causing the two retaining members to move to a separated extended position of maximum spacing. When an inward force is applied against the retaining member in the direction of the tube length, the retaining plate moves to a closer position so that when between a pair of vise jaws the retaining members resiliently urge a pair of parallels against the vise jaws.
The holder device disclosed in Montgomery is the current state of the art for holding parallels apart in a vise as indicated by the fact that it is believed by the inventors that the device is the primary device used and sold in the United States for this purpose. As indicated in the various blogs, the commercial embodiment of Montgomery lacks various features. While it functions, it is complicated and is replaced often.
There exists therefore a need for a simpler, yet more robust solution and kit for use in a machine shop.